Such a conventional technique is described that drives a cam by transmitting rotation of a crankshaft to a cam drive sprocket through an intermediate idling shaft and other shafts and transmitting rotation of the cam drive sprocket to a cam driven sprocket through a cam chain (see Patent Literature 1, for example).
Furthermore, relating to a chain driving mechanism that transmits driving force to a supercharger, such a structure is disclosed that takes out the driving force from an inner side of a crankshaft with respect to a cam chain disposed on a side of the engine (for example, see Patent Literature 2).